Jeska, Thrice Reborn

Her starting loyalty is a scoreboard of how many times you've already cast a commander this game. Cast fresh from the command zone as your first commander, she counts that very casting and enters with a single loyalty counter: enough to survive as a state-based action, but not by much. The interesting math is in the recasts. Every time the command tax sends a commander back to the zone and out again, Jeska arrives heavier the next time, so she asks for a deck willing to sacrifice or bounce its own commanders on purpose. Her zero-cost ability is why she matters before she has counters to spend: tripling one creature's combat damage to a single opponent can turn a lone connection into a kill, and it ignores her own loyalty entirely. The minus-X, a triple-target burn spell, only comes online once you've banked the counters, so the two halves pull against each other (one free and immediate, the other the payoff for patience). Because she can be your commander and carries Partner, she invites a two-color pairing where the second commander is the recastable body doing the sacrificing, feeding her loyalty from the zone with every cycle. The wager underneath is that a walker's numbers matter less than how many times you're willing to keep bringing her back.